It has been known that exposure to a tiny amount of fluoride may help prevent tooth caries, but if the exposure is too much, this neurotoxin can cause a much more serious dental disease called fluorosis.
A new study published online Oct 20, 2011 in Journal of Public Health Dentistry showed that in fluoridated areas, usinginfant formula together with tap water increased risk of fluorosis, and if using infant formula but not using non-tap water, then infants were at higher risk for caries. The study also found higher prevalence of fluorosis in fluoridated areas, compared to non-fluoridated areas.
Infant formula often contains higher levels of fluoride and when an infant uses both fluoridated tap water and infant formula, he or she is known to be at higher risk for fluorosis and the current study provides evidence to validate the concern.
For the study. L.G. Do of The University of Adelaide in Australia and colleagues recruited 588 children whose exposure to fluoride in early childhood was surveyed. Children aged 8 to 13 years of age were examined for fluorosis using the Thylstrup and Fejerskov Index and children were examined at 8 to 9 years of age for tooth caries.
Based on the infant formula feeding and fluoridation status, considered in the study were three groups in non-fluoridared areas (formula non-user, user for less or equal to six months and user for more than 6 months and four groups in fluoridated areas (nonuser, user with nonfluoridated water, user with fluoridate drinking water for less than or equal to 6 moths and user with fluoridated tap water for more than six months.
The researchers found
1. Children in fluoridated areas had higher incidence of very mild to mild fluorisis, but lower incidence of tooth caries, compared to those in nonfluoridated areas; This observation suggests that fluoridation may increase risk for very mild or mild fluorosis, but reduce risk of tooth caries.
2. Of children in nonfluoridated areas, formula users for longer than 6 months had a significantly higher prevalence of fluorosis, compared with non-usrs; This observation indicates that using infant formula for longer than six months may increase risk of fluorosis even in areas where water is not fluoridated.
3. In fluoridated areas, the formula users regardless of using fluoridated water or not had the same prevalence of fluorosis; This indicates that both infant formula and fluoridation may increase risk of fluorosis.
4. In fluoridated areas, formula users with nontap water had a high prevalence of tooth caries.
The researchers concluded “Infant formula use was associated with higher prevalence of fluorosis in nonfluoridated areas but not in fluoridated areas. Type of water used for reconstituting infant formula in fluoridated areas was associated with caries experience.”